When you first experience pain, it is a symptom of illness or injury in the part of your body that is having the pain. The sudden onset of pain is called acute pain.  It gets your attention and prompts you to take action to prevent further worsening of the condition causing the pain.  This could be a simple action such as the reflex that makes you jerk your hand off a hot stove, or it could be more complex such as cooling, resting, or elevating an injured ankle.  Or the pain could prompt you to see a doctor.  We always take for granted that we will feel good most of the time so when pain strikes, we feel bad.  Pain interrupts our work, our recreation, and our relationships with our families and disrupts our daily normal activities. Your basic goal if you are sick is to be comfortable and not being in pain, likewise the goal of treatment for the doctor who is treating you for any illness, but especially for an illness associated with chronic pain.  Once the cause of your pain is found and proper chronic pain treatment is started, the pain may serve the useful function of keeping you at rest so that the injury or illness can heal.  But if the pain comes from an illness that is incurable and will never heal, the pain losses its usefulness and becomes harmful.  This type of pain keeps you from normal daily activities and inactivity decreases your strength.